Rate and equilibrium constants for hydrolysis and isomerization of (E)‐ and (Z)‐p‐methoxybenzaldehyde oximes

摘要: The interconversion and hydrolysis of (E)- (Z)-oximes p-methoxybenzaldehyde in aqueous solutions perchloric acid have been studied the concentration range from pH 3 to 11M. Kinetic measurements confirm that isomerization proceed through a common tetrahedral intermediate T 0 . At low concentrations, attack water on protonated oxime is rate-determining reaction no separate observable. However, as increases becomes faster than loss hydroxylamine To E Z observable competition with hydrolysis. From kinetic equilibrium comprehensive set rate constants for protonation, hydration derived. For neutral oximes K = [E]/[Z] 8 pK -0.55 0.80 isomers, respectively. By combining these values formation hydroxylamine, including d =[T ]/ [aldehyde][NH 2 OH] [T ]/[oxime] 1.8, R -3.65 -5.90 H O 6.3 x 10 - 5 7.9 6 may also be , are compared corresponding forp-methoxybenzaldehyde its hydrate (= To).